CAPRISA explains high HIV infection rates in young women

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Three studies released by the Durban-based Centre of the Aids Programme of Research in South Africa (Caprisa) provided new evidence on the factors contributing to the high rates among this population sector, prompting director Salim S Abdool Karim to comment that reducing new HIV infections in young women was “one of Africa’s greatest challenges”, reports Nicola Jenvey writing for MedicalBrief.

“Implementing targeted prevention interventions to break the HIV transmission cycle while treating bacterial vaginosis can reverse the impact of the HIV epidemic in young people,” he said.

The Caprisa-led studies [N1] sought to explain why young women have high HIV rates. One study analysed the genetic HIV code from 1,589 HIV-positive people to better understand the persistent spread of HIV in a rural and an urban South African community.

Karim said the study revealed a cycle of HIV transmission driven by high rates of new HIV infections in adolescent girls and young women from men typically eight years older than them. Many of those men were also partners to similarly-aged women, among whom the HIV prevalence exceeded 60%.

Two additional studies investigated the role of vaginal bacteria in HIV risk. One examined the vaginal bacteria of 120 women and found those with an overgrowth of Prevotella bivia were almost 20 times more likely to acquire HIV than those with low levels or an absence of this vaginal bacterium.

The third study, which analysed 3,334 genital bacterial proteins from 688 women, showed 60% with “healthy” (lactobacillus-dominant) vaginal bacteria benefitted from tenofovir gel pre-exposure prophylaxis (PReP). The balance did not.

Karim said follow-up laboratory studies showed the vaginal bacteria Gardenerella vaginalis, predominates in the vagina when lactobacillus was not, absorbed tenofovir and reduced its availability in the genital tract to prevent HIV infection.

Various studies released by the National Institutes of Health (NIH) subsidiary, the National Institute of Allergy and Infectious Diseases (NIAID), during Aids 2016 has prompted good news among researchers as it offered hope for limiting new infections.

An analysis of the landmark ASPIRE (A Study to Prevent Infection with a Ring for Extended Use) vaginal ring study found using a drug-infused vaginal ring most or all the time reduced the risk of HIV infection in women by at least 56%. The ring, which continuously releases the anti-HIV drug dapivirine, safely reduced the risk of HIV infection by 27% in the ASPIRE study population overall and by 61% among participants aged 25 years and older.

NIAID director Dr Anthony Fauci said consequently another clinical trial will be launched this month building on ASPIRE by gathering data on whether and how women use the ring knowing it was safe and moderately effective.

Called the HOPE (HIV Open-Label Extension) study, this follow-on trial will further examine the relationship between adherence to the ring and protection from HIV infection and gather data on the extended safety of the monthly ring. It will be held via former ASPIRE study sites in Malawi, South Africa, Uganda and Zimbabwe.

NIAID primarily funded the ASPIRE, HOPE and the exploratory analysis research studies.

Fauci said the ASPIRE study reflected the level of protection the dapivirine ring afforded, but stressed HIV prevention tools “only work if people use them”. Further studies aimed to give credence to the hypothesis that greater adherence translated into a higher level of protection.

Fauci said a series of studies from the PROMISE trials also provided “encouraging data” on options for preventing mother-to-child transmissions during extended breastfeeding, but also raises concerns about treatment adherence and acceptance among HIV-positive women who had recently given birth.

The third study shows high efficacy and safety of a simplified, fixed-dose combination regimen for treatment-naïve women.

Aids 2016 international chair Chris Beyrer said these new insights paved the way for developing new prevention and treatment approaches to protect the health of women, girls and newborns. Given women account for the majority of adults living with HIV in sub-Saharan Africa and new infections among them were double that of young men, it had “never been more critical to address this vital issue”.

Caprisa material

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